Blar i NTNU Open på forfatter "Vullum, Per Erik"
-
Quantitative (S)TEM analysis of intermediate band solar cell materials
Nord, Magnus Kristofer (Master thesis, 2011)In this thesis the strain properties of two InAs/GaAs quantum dot intermediate band solar cell materials have been explored. Both samples were thin films grown on a (100) GaAs substrate. The quantum dot material was InAs, ... -
Quantitative strain analysis of InAs/GaAs quantum dot materials
Vullum, Per Erik; Nord, Magnus Kristofer; Vatanparast, Maryam; Thomassen, Sedsel Fretheim; Boothroyd, Chris; Holmestad, Randi; Fimland, Bjørn-Ove; Reenaas, Turid Worren (Journal article; Peer reviewed, 2017)Geometric phase analysis has been applied to high resolution aberration corrected (scanning) transmission electron microscopy images of InAs/GaAs quantum dot (QD) materials. We show quantitatively how the lattice mismatch ... -
Relationship between Al-Ni intermetallic Phases and Bond Strength in Roll Bonded Steel-Aluminum Composites with Nickel Interlayers
Arbo, Siri Marthe; Bergh, Tina; Holmedal, Bjørn; Vullum, Per Erik; Westermann, Ida (Journal article; Peer reviewed, 2019)In this work, the interface characteristics and resulting bond strength were investigated for roll bonded steel-aluminum composites with nickel interlayers, both after rolling and after post-rolling heat treatments at 400 ... -
Selective area growth of AlGaN nanopyramid arrays on graphene by metal-organic vapor phase epitaxy
Munshi, A Mazid; Kim, Dong-Chul; Heimdal, Carl Philip J; Heilmann, Martin; Christiansen, Silke; Vullum, Per Erik; Van Helvoort, Antonius; Weman, Helge (Journal article; Peer reviewed, 2018)Wide-bandgap group III-nitride semiconductors are of special interest for applications in ultraviolet light emitting diodes, photodetectors, and lasers. However, epitaxial growth of high-quality III-nitride semiconductors ... -
SiC crystalline micro bullets on bio-carbon based charcoal substrate
Jayakumari, Sethulakshmy; Vullum, Per Erik; Van Helvoort, Antonius; Tangstad, Merete (Peer reviewed; Journal article, 2020)Silicon carbide (SiC) micro bullets were grown on a bio-carbon based charcoal substrate, the morphology and crystal structure were analyzed. In order to collect the crystallographic details scanning electron microscopy ... -
Silicon-carbon composite anodes from industrial battery grade silicon
Foss, Carl Erik Lie; Andersen, Hanne Flåten; Ulvestad, Asbjørn; Kirkengen, Martin; Vullum, Per Erik; Voje, Jorunn; Tronstad, Ragnar; Mokkelbost, Tommy; Mæhlen, Jan Petter (Journal article; Peer reviewed, 2019)In this work, silicon/carbon composites for anode electrodes of Li-ion batteries are prepared from Elkem’s Silgrain® line. Gentle ball milling is used to reduce particle size of Silgrain, and the resulting Si powder consists ... -
Solvent-Controlled Charge Storage Mechanisms of Spinel Oxide Electrodes in Mg Organohaloaluminate Electrolytes
Wang, Lu; Wang, Zhaohui; Vullum, Per Erik; Selbach, Sverre Magnus; Svensson, Ann Mari; Vullum-Bruer, Fride (Journal article; Peer reviewed, 2017)Considering the improved safety, reduced cost, and high volumetric energy density associated with Mg batteries, this technology has distinct advantages for large-scale energy storage compared to other existing battery ... -
Sponge-like porous manganese(II,III) oxide as a highly efficient cathode material for rechargeable magnesium ion batteries
Wang, Lu; Asheim, Karina; Vullum, Per Erik; Svensson, Ann Mari; Vullum-Bruer, Fride (Journal article; Peer reviewed, 2016)Here, we are the first to report a spinel type Mn3O4 as cathode material for Mg-ion battery (MIB) with graphite foil (Gif) as current collector. High Coulombic efficiency and good cyclic stability of Mn3O4 are demonstrated, ... -
STEM-EDS of Inception Sites of Vented Trees in a HV XLPE Subsea Cable
Hårberg, Sofie Brandtzæg; Nylund, Inger-Emma; Einarsrud, Mari-Ann; Vullum, Per Erik; Lesaint, Cedric Michel; Hvidsten, Sverre (Chapter, 2023)High voltage XLPE cable cores have been subjected to wet ageing following the recommendations in CIGRE TB 722. The electrical ageing was performed at 500 Hz and 10 kV/mm. Vented water trees were detected initiating and ... -
Strategy for reliable strain measurement in InAs/GaAs materials from high-resolution Z-contrast STEM images
Vatanparast, Maryam; Vullum, Per Erik; Nord, Magnus Kristofer; Zuo, Jian Min; Reenaas, Turid Worren; Holmestad, Randi (Journal article; Peer reviewed, 2017)Geometric phase analysis (GPA), a fast and simple Fourier space method for strain analysis, can give useful information on accumulated strain and defect propagation in multiple layers of semiconductors, including quantum ... -
Structural investigation of epitaxial LaFeO3 thin films on (111) oriented SrTiO3 by transmission electron microscopy
Christiansen, Emil; Nord, Magnus Kristofer; Hallsteinsen, Ingrid; Vullum, Per Erik; Tybell, Per Thomas Martin; Holmestad, Randi (Journal article; Peer reviewed, 2015)We report on structural domains in LaFeO3 epitaxial thin films on (111) oriented SrTiO3 observed by transmission electron microscopy using low magnification dark field imaging and high resolution transmission electron ... -
Study of solid state phase transformations and precipitation in Ti-6Al-4V exposed to thermal cycling in additive manufacturing process
Araya, Susanne (Master thesis, 2018) -
Thermal Conductivity of A-site Cation-Deficient La-Substituted SrTiO3 Produced by Spark Plasma Sintering
Loland, Thomas Emdal; Sele, Jaran; Einarsrud, Mari-Ann; Vullum, Per Erik; Johnsson, Mats; Wiik, Kjell (Journal article; Peer reviewed, 2015)During the last decade oxide-based thermoelectric materials have received increased attention due to their high stability and thermal robustness at high temperatures as well as the availability and nontoxic nature of a ... -
Understanding Capacity Fading of MgH2 Conversion-Type Anodes via Structural Morphology Changes and Electrochemical Impedance
El-Kharbachi, Abdelouahab; Hu, Yang; Sørby, Magnus Helgerud; Vullum, Per Erik; Mæhlen, Jan Petter; Fjellvåg, Helmer; Hauback, Bjørn (Journal article; Peer reviewed, 2018)Previous studies have demonstrated that MgH2 is a promising conversion-type anode toward Li with high capacity (2037 mAh/g) and low discharge/charge overpotential hysteresis. A major challenge is the capacity loss after a ... -
β- and δ-Al-Fe-Si intermetallic phase, their intergrowth and polytype formation
Becker, Hanka; Bergh, Tina; Vullum, Per Erik; Leineweber, Andreas; Li, Yanjun (Journal article; Peer reviewed, 2019)Crystal structure characteristics of coexisting β and δ phase were investigated in a purely intermetallic Al-Fe-Si alloy and in plate-shaped intermetallic particles formed in a model secondary Al7.1Si1.2Fe0.3Mn alloy. The ...